The invention relates to an adjustable steering column for a motor vehicle with a mounting unit, securable in position on the chassis of the motor vehicle, and a setting unit adjustable with respect to the mounting unit. The setting unit rotatably bearing supports a section of the steering spindle, which section adjoins a steering wheel-side end of the steering spindle, which end, during the displacement of the setting unit with respect to the mounting unit, is displaceable between a first end position and a second end position over a setting path. At least coupled over a portion of the setting path, a displacement of the steering wheel-side end takes place in a direction of a length adjustment of the steering column and in a direction of a height or inclination adjustment of the steering column. On the setting unit or on the mounting unit a frontward guide bolt is secured which engages into at least one frontward elongated hole provided in the other of these two units.
Adjustable steering columns are known in various embodiments. The adjustability of the steering column in order to adjust the position of the steering wheel represents a convenience function for the driver.
Apart from length-adjustable steering columns and steering columns only inclination or height adjustable, steering columns length as well as also height or inclination adjustable are also known.
Steering columns length adjustable as well as also inclination or height adjustable are disclosed, for example, in EP 1 364 856 A1. A clamp bolt of a securement device, with which the set position of the steering column can be arrested, penetrates crossing elongated holes in a chassis-stationary mounting unit and in a setting unit adjustable for setting the position of the steering column with respect to it, which setting unit rotatably bearing supports a section of the steering spindle. During the adjustment of the inclination or height, the clamp bolt is displaced in elongated holes extending in this direction. The setting unit is swivelled about an axle bolt which is further removed from the steering wheel-side end of the steering spindle than the clamp bolt. In order to permit the length adjustment of the steering spindle, the chassis-stationary axle bolt is guided such that it is displaceable in elongated holes of the setting unit which extend parallel to the axis of the steering spindle and are located parallel to the elongated holes in the setting unit penetrated by the clamp bolt and serve for the length adjustment. Setting the length and the inclination or height can herein be carried out independently of one another.
A similar design is also disclosed in U.S. Pat. No. 6,189,405 B1. Here the bolt, further removed from the steering wheel-side end, is guided such that it is displaceable in elongated holes in the setting unit parallel to the longitudinal axis of the steering spindle as well as also in elongated holes extending at right angles thereto in the chassis-stationary mounting unit. This bolt represents a clamp bolt of a further securement device, which device is coupled with the securement device, of which the clamp bolt, further removed from the steering wheel-side, is a part. Through this design, which however is rather complex, additional adjustment feasibilities of the steering wheel result.
EP 0 671 308 B1 and EP 0 440 698 B1 furthermore disclose so-called “head tilt” steering columns. The axle bolt, about which the swivel axis of the height or inclination adjustment takes place, is here located closer to the steering wheel-side end than the clamp bolt, whereby a large setting range for the height or inclination adjustment results. The steering wheel can hereby be swivelled away upwardly when getting into or out of the car. Due to the proximity of the swivel axis to the steering wheel, the plane in which the steering wheel is located herein changes markedly in the height or inclination adjustment.
A similar steering column is also disclosed in EP 121 506 B1. However, here the chassis-stationary mounting unit includes a larger window clearance in which the clamp bolt can be moved freely in order to carry out the length adjustment and the height or inclination adjustment.
A steering column of the type described in the introduction is disclosed in DE 10 2004 011 657 A1. The length adjustment and the height or inclination adjustment are executed under coupling. For this purpose, a guide bolt attached on the setting unit engages into an elongated curved hole extending in the mounting unit. The inclination or height adjustment takes place about an axle bolt, over which a bearing sleeve is swivellably bearing supported with respect to the mounting unit. The bearing sleeve, in turn, supports the steering spindle in a region further removed from the steering wheel-side end than the region supported by the setting unit.